1. Field of the Invention
The field of the invention is that of optoelectronic power devices, the active part of which is constituted by an integrated circuit assembling a plurality of semiconductor lasers.
More specifically, this integrated circuit brings together a plurality of elementary lasers capable of generating power in the range of one watt and hence capable of having optical sources of power of nearly one kilowatt. Typically, these elementary lasers are associated in mutually parallel linear arrays or strips on the chip of semiconductor material. The arrays are raised with respect to the surface of the substrate in such a way that they have two raised faces needed for the operation of each elementary laser. These faces are parallel to the surface of the substrate. Two sets of mirrors, positioned between the laser arrays, reflect the light beams at 90.degree. and send them back perpendicularly to the surface of the substrate. These mirrors are generally formed by the machining of the substrate in planes inclined at 45.degree. and are then covered with at least one metal layer that is used both as an optical reflector and as an electrical conductor. In general, a first contact-making metallization is deposited on each laser array (M.sub.e) and a second contact-making metallization (M.sub.R) is deposited on each reflector. All the flanks of the reflectors are also covered with a metallization (M'.sub.R) to provide said reflective elements with high reflecting capacity. FIG. 1 shows a view in perspective of an exemplary integrated circuit with surface-emitting lasers. The metallised flanks of the 45.degree. reflectors give rise to the desired surface emission.
2. Description of the Prior Art
In the prior art, the reflectors are generally obtained through etching by the ion machining of a substrate made of semiconductor materials of the III-V group. Then, in a second stage, deposits are made by epitaxial growth of the successive layers need to prepare the laser structure.
This type of method then includes a phase, which is always a difficult one, of conditioning the surface of the sample in order to prepare the renewal of epitaxial growth of the laser structure on the etched substrate.
In order to avoid this step of ion machining followed by the renewal of epitaxial growth of the laser structure on the 45.degree. reflectors that are formed beforehand, the invention proposes a method of manufacture enabling the preparation of Bragg reflectors forming an angle .theta. with the substrate (this angle could be typically equal to about 45.degree.). This is done through selective epitaxial growth by means of a mechanical mask. The making of such reflectors then makes it possible to eliminate the subsequent step of metallization of the reflectors as practised in the prior art. This is always a difficult step if it is desired not to damage the active faces of the laser structures, for these faces are very close to the reflecting flanks.